Shanghai Ruigu analytical method for obstructing moisture-resistant microbial penetration
1 bacterial preparation
Staphylococcus aureus ATCC 29213 was cultured on tryptic soy agar at 36 ° C ± 1 ° C for 18-24 h, and 2-3 colonies were inoculated into 3 ml trypsin soy broth and cultured at 36 ° C ± 1 ° C for 18-24 h. . The final bacterial suspension was counted by diluting 1:10 with peptone water to a concentration of 1 x 104 CFU/mL to 4 x 104 CFU/mL.
Open the sterile bag and take out the polyurethane film that is still attached to IQ. Place the wettable polyurethane film of the carrier material on the cleansing plate face up. For the convenience of operation, use the double-sided tape to place the four corners of the carrier material. Fixed to the plate. A corresponding area was formed on the carrier membrane using the petri dish cover as a template, in which 1.0 ml of the S. aureus suspension was applied, and then the pieces were dried at 56 ° C for about 30 min, and the sterilized glass was used during the drying. The applicator continues to coat the bacterial suspension on the carrier membrane to evenly distribute the bacterial liquid.
The tablets are used on the same day after preparation.
2 state adjustment
If necessary, adjust the condition of the test piece according to GB6529, or perform the state horizon and test under the standard normal room temperature conditions. The method of state adjustment should be recorded in the test report.
3 test settings
Adjust the weight on the control rod so that the force applied to the agar on the test finger is 3N ± 0.02N.
Place the first agar dish on the turntable.
4 Material application
The following counts were used: a circular weight consisting of inner and outer rings was used with a total weight of 800 g ± 1 g to apply a standard tension to the material. Place the cylinder in the center of the inner ring, and then cover the test piece on the cylinder and the inner ring. Place the bacteria on the specimen after removing the attached paper on the test piece. Finally, the polyurethane film is covered with a layer of HDPE film, and the outer ring is pushed down so that the three layers of material are firmly added between the two rings.
5 test
Gently place the above ring assembly on the first agar culture dish to the lower lid. The steel ring is freely suspended on the outside of the rotating disk, and the test finger is placed on the HDPE film in the mouth of the dish, so that the test piece can be Contact with the agar surface. The test refers to the application of 3N pressure as specified above, which is 15 minutes of operation of the instrument.
Immediately after 15 minutes, remove the ring kit and set it aside.
Remove the first Petri dish from the rotating disc and place the lid. Place the second petri dish and ring kit on the rotating plate immediately.
Perform the above steps for the next four petri dishes with the same loop assembly.
After the five petri dishes were tested, the chips were removed and discarded, and the test pieces were reversed and covered with a HDPE film facing downward.
The first parallel test group was completed by operating on the sixth petri dish for 15 min.
The remaining four test pieces were also run for six minutes each of the six culture dishes as described above, and each piece was subjected to a freshly prepared mushroom piece.
If the surface of the agar has a liquid, it is placed on a clean bench to dry, and each agar dish is capped and placed at 36 ° C ± 1 ° C for 48 h.
The number of Staphylococcus aureus colonies in each dish was counted, and the number of colonies in the radius of the 15 minute center of the dish was not counted.
If the count of the right or more dishes is greater than 750 CFU (excluding the number of colonies in the 15 min radius region of the center of the culture dish described above), the test can be re-awakened. If the retest is still one or more dish counts greater than 750 CFU, indicating that the material is unlikely to have sufficient barrier properties, the test can be terminated.
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